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regulation of hypha formation by an essential G1 cyclin of Candida albicans

Reference	BB/C514566/1
Principal Investigator / Supervisor	Professor Peter Edwin Sudbery
Co-Investigators / Co-Supervisors
Institution	University of Sheffield
Department	Molecular Biology and Biotechnology
Funding type	Research
Value (£)	224,297
Status	Completed
Type	Research Grant
Start date	01/08/2005
End date	31/07/2008
Duration	36 months

Abstract

The human fungal pathogen C. albicans can switch growth forms between yeast, pseudohyphae and hyphae, an ability that is thought to be essential for pathogenesis. In preliminary observations we have found that the G1 cyclin, Cin3 is essential for viability. However, when cells are depleted of Cin3 using the conditional MET3 promoter, yeast cells spontaneously form hyphae. This observation not only provides the opportunity to study the regulation of hypha formation, but also investigate an unexpected role of CLN3, which because it is essential, constitutes a potential drug target. The proposal describes four possible hypotheses describing the role of Cln3, and proposes experiments by which they may be tested. 1) Cln3 negatively regulates the expression of the hyphal-specific G1 cyclin Hgc1. Tested by: a) Hgc1 expression in Northern blots, b) the effect of ectopic expression of HGC1 in CIn3-depleted cells. 2) CIn3-depletion results in a change in the transcriptional program that results in hyphal formation. Tested by: a) microarray analysis of Cln3-depleted cells, b) candidate genes, which show regulation specific to Cln3-depletion, will be investigated further by standard methods such as i) the effect of gene deletion, ii) cellular localisation of YFP fusions, iii) formation of complexes using TAP-tagged versions. 3) Cln3 depletion completely reduces or abolishes the transcription of key genes required for start. Hyphal formation is a consequence of the resulting G1 arrest. Tested by: a) constructing an analogue sensitive and its alleles of CDC28 to arrest cells in G1 independently of CIn3-depletion. 4) Signal transduction pathways that induce hyphal formation converge on Cln3. Tested by: a) determining the epistatis relationships between the signal transduction pathways and CIn3-depletion, b) construction of strains in which CIn3 is either stabilised or its action enhanced, which is predicted to impair hyphal formation, c) monitoring CLN3 transcript and protein levels after hyphal induction, d) monitoring CIn3 protein localisation after hyphal induction.

Summary

unavailable

Committee	Closed Committee - Biochemistry & Cell Biology (BCB)
Research Topics	Microbiology
Research Priority	X – Research Priority information not available
Research Initiative	X - not in an Initiative
Funding Scheme	X – not Funded via a specific Funding Scheme

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